


A theory of exaptation

by myoue



Category: Shingeki no Kyojin | Attack on Titan
Genre: Canon Era, Developing Relationship, M/M
Language: English
Status: Completed
Published: 2015-08-23
Updated: 2015-08-23
Packaged: 2018-04-16 17:30:51
Rating: Mature
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 1,793
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/4634007
Author URL: https://archiveofourown.org/users/myoue/pseuds/myoue
Summary: <blockquote class="userstuff">
              <p>It just so happened that the thumping was irrevocably loud beside Levi’s head as Eren lay beside him, arm slung over his shoulder and neck, breathing as steadily as Levi's own heartbeat.</p>
            </blockquote>





	A theory of exaptation

**Author's Note:**

> someone recently reminded me that i had this story, and i had it on ao3 a while ago even though i deleted it after a couple days. but i decided to give it a bit of a rewrite and repost it because i do kind of like it lol

The heart beats to circulate blood around the body to keep you alive. It just so happens that the beating also causes a noise—a soft thumping—that has no particular advantage or disadvantage. It is considered an irrelevant side effect to the main function.

It also just so happened that the thumping was irrevocably loud beside Levi’s head as Eren lay beside him, arm slung over his shoulder and neck, breathing as steadily as Levi's own heartbeat.

-

One recruit had always stood out to Levi for running harder, faster than the others, and almost always in a state of tired exertion as if he was so focused on the task at hand that he hadn’t realized that he'd been wheezing and short on breath the whole time. He was on the ground more than the others, upside down in a tangled mess, and still in the air even when the sun had long exhausted and everyone else had headed back.

“One more!” he would shout at them through the trees as they gave him sympathetic looks, leaving while there was still daylight to make their way back. Levi had no idea what he was doing there.

“Give it a rest.”

Levi would swing down as Eren began to fiddle with the dials on his gear.

“C-Captain.” Eren looked up at him. He stood his ground, trying to seem tough in front of a superior when instead all he looked like was downright intimidated. “The sun hasn’t gone down yet,” he insisted. “There’s still time for more.”

It would have fallen on deaf ears, but now that Levi was down here he could clearly see those eyes that told him there was nothing much he could do. He didn't want to deal with dragging someone back kicking and screaming.

“I’m not a fan of your enthusiasm.”

He really should have just gone back.

Improving, at least in Eren’s case, involved learning visually. He would watch first, match Levi’s gestures later, and copy them the best he could without flinging himself into a tree. Although, that did happen more times than Levi could count. (It would eventually lead to lonely moonlit nights in the infirmary, applying medicine to Eren’s face and ignoring every question thrown at him asking why he’s doing this when Eren can already heal on his own.)

It was through this daily process that Levi had started to notice something peculiar as he flew complicated motions through the air. It was hard to catch at first, he wasn’t even sure if it was there at all, but Eren’s eyes seemed to linger on him, like he was deeply involved with watching something other than what Levi was trying to explicitly teach him.

It became apparent when Levi had touched him, just lightly on the chin in an attempt to explain where his head should be when on a downward spiral to the ground. Eren had flinched, breath hitched, and lip drawn into his teeth as he’d stared wide-eyed at the ground.

Those eyes stared anywhere but at him for the rest of the night, which meant that any more teaching became a waste.

Regardless, Eren would eventually learn to fly through the air like a pro. But Levi couldn't help but think there was something else unnecessary that developed out of that whole event, as he reminisced for the first time how soft a recruit’s face could feel on his fingertips.

And it would feel especially soft as it was dug into the crevices of Levi’s neck later on, hot breath coming out in puffs that burned his skin. The teeth that drew in his lip now drew in the skin under Levi’s jaw in a searing open-mouthed kiss.

-

There was good reason to believe that the tongue and mouth meant for speaking came out of a happenstance evolutionary advantage, existing at first as an accident and then becoming immensely important for communication.

“Morning, Captain,” Eren would start to say to him in the hallways.

“Do you think you could help me study? We have a test on Wednesday on Titan movement patterns.”

“Are you going out to the stables to feed the horses? Can I come?”

“What do you think about cats, Captain? I found one out in the yard and I’m wondering if they have any rules on letting us keep them in our rooms.”

It would catch him a bit off guard if Eren happened to start speaking before Levi had even noticed him bounding up to him, like he was so excited to see Levi that he couldn't keep it in.

But it didn’t escape Levi’s notice the fact that Eren was slowly creeping up on him, and Levi wasn’t sure he particularly minded. Eren seemed quite taken with the idea of cats snuggling up around Levi's feet.

“You’re talking a lot lately, Captain,” Eren had said, looking almost pleased with himself like this had been his goal all along.

Levi snorted unseemly. “Maybe it’s you who’s talking about more interesting things lately.”

Eren only laughed. “Maybe you’re right.” Then he grinned like he wanted Levi to ruffle up his hair the way he might ruffle up a cat's.

Nowadays, this whole back-and-forth during Levi’s trips to the fields and the mess halls and his room became somehow unnecessary and yet inexplicably necessary to his life. It became, dare he say, exciting to look forward to times when he’d bump into Eren in the halls, watch him flustered and red when he genuinely didn’t know Levi was there, and, the most amusing of all, feigned surprised when Eren tried to pretend like he wasn’t watching Levi all hour from across the grass during combat practice outside.

“Enough of the excuses,” Levi would tell him, but it didn’t stop Eren, not even a little bit.

The mouth that was always chattering away would soon become good for other things as well, slotted into his when their moans became too loud while the walls were too thin. Eren would whisper things that Levi wouldn’t be able to hear, being too far gone to understand a single thing.

-

Eren was a very physical person—not to say that he wasn’t intelligent—but it became obvious that sitting and internalizing theory about agency loss in Titans during night time wasn’t his optimized style of learning. He became crankier at an exponential rate the longer he sat at a table instead of outside even just doing laps, forced to tap his foot against the leg of the desk like he was trying to push time by faster.

In fact, there were specific times when Eren performed at his best—during the slow dance of combat. There was a certain look Levi attributed to this state, and it was whenever Eren slid with overdramatic flair through the air, tapped the trees with his foot and a glance back at Levi, before he was flying off again, flashing the eyes of something that sent volts of electricity through Levi.

For a while, Eren made things so goddamn hard. Outgrowing his shirts and putting on so much mass that Levi had to move out of the way for him sometimes, often being pushed and knocked to the side, into corners, into closets. Eren had claimed he didn’t notice a thing, and that only made Levi inextricably angrier when he couldn’t argue back without saying more than necessary.

So instead Levi started saying, “You’re getting taller.”

And there was a point where Eren had changed his entire demeanour to say “Yeah, I have” with a smirk and a grin and a push to the sheets.

It was even harder to remember just how it all started when Levi was grasping at the headboard, back arching off the bed when Eren had thrust especially hard into him. He would have that focused glare on his face as he looked down on Levi, now marred with a harsh and furious redness against his cheeks, a glazing over of his eyes driven high with lust, and a high-pitched gasp whenever Levi unintentionally squeezed tight around him.

Levi would demand more and Eren would meet it, going faster and giving more and more and more because this was one of those times when Eren was perfect, glorious, and gave nothing less.

The bed clashed against the wall, far too noisily than Levi gave a shit about, and Eren crashed his lips against his if not in an attempt to drown out the rocking of the bed than to drown out the noise of his thoughts. It worked—as he melted, melted, melted into Eren, and he could feel nothing else but Eren’s cock sliding in and out of him and the thrill that ran through his veins lighting up his every nerve.

Eren kissed his neck, mumbling and murmuring things against it that Levi wasn’t sure were real words or if they were simply nonsensical moans. His hearing wasn’t gone, but it might as well have been considering he couldn’t hear himself at all. Eren would growl back every time Levi felt an onslaught of his breath release from his hollow throat. Every time Eren’s hands would trail from caressing his thighs to rubbing hard circles into his sides to flattening against his leaking cock and pressing it to his stomach, Levi would find that he was already out of breath.

“I love you,” Eren rasped out, and despite Levi thus far being unsure of his hearing, he would still be able to pick out those words from Eren’s mouth—even if they were out of a raging thunderstorm, out of a tsunami crashing waves against a beach, and out of the thick haze of this darkened room with their loud intermingled panting.

It didn’t take much more than that whisper against Levi’s ear for him to come, shaking and clawing at the skin of Eren’s back. Eren fell to the side of him once he did, chest still heaving from exertion and heartbeat running erratically.

Eren couldn’t keep awake long enough to hear an answer to his confession, although Levi was sure he knew the answer to it already.

In turn, Levi would know intimately that Eren meant every word of that confession as soon as he felt Eren sling an arm across his body in the middle of drifting off to sleep.

He would know that he and Eren being in this kind of relationship was merely a side story among a defined set of more important aspects of their lives, something that only just happened to distinguish itself out of a whole load of unintentional possibilities.

And Levi would also know that Eren, being all that he was, would still be worth it in the long run.

 

 


End file.
